Calcium phosphates such as hydroxyapatite have been widely used in the medical field as biocompatible materials. Particularly, composite materials produced by coating the surface of a base material with calcium phosphate are expected to be applied as percutaneous devices such as catheters because the composite materials have high cellular adhesiveness. For example, there has been suggested a technology of binding fine particles of calcium phosphate to the surface of a flexible polymer base material such as cyclofibroin, and using the composite in a percutaneous device.
Here, as a technique of fixing hydroxyapatite to the surface of a base material, for example, there has been suggested a method of selecting a polymer base material having a particular functional group such as an isocyanate group or an alkoxysilyl group as a polymer base material, and bonding hydroxyapatite to the polymer base material (Japanese Patent Application Laid-Open (JP-A) No. 2004-51952, hereinafter referred to as Patent Document 1). In addition to that, there has been suggested a method of forming hydroxyapatite on the surface of a polymer, the method including a step of immersing a substrate which has at least the surface hydrophilized by a corona discharge treatment, a graft treatment or the like alternately in a calcium solution and a phosphoric acid solution, and producing and fixing hydroxyapatite at least on the surface of the substrate (JP-A No. 2000-327314, hereinafter referred to as Patent Document 2).
Furthermore, as a method of fixing hydroxyapatite on the surface of a metal, there has been disclosed (in OKADA, M., et al., J. Biomed. Mater. Res. Part A, 589-596, 2008, for example, hereinafter referred to as Non-Patent Document 1) a method of treating the surface of stainless steel with nitric acid, subsequently treating the surface of stainless steel with a silane coupling agent (SCA) such as (3-mercaptopropyl)triethoxysilane, graft polymerizing γ-methacryloxypropyltrimethoxysilane (MPTS) to the silane coupling agent that has been introduced to the metal surface by using 2,2-azobis(isobutyronitrile) (AIBN), and fixing hydroxyapatite onto the metal surface by a reaction between the trimethoxysilyl residue of the polymer and hydroxyapatite.